Digital picture systems in general convert picture and sound signals into a digital format. Examples of such systems include high definition TV (HDTV), digital video cassette recorder (D-VCRs), laser disk players (LDPs), etc. They must synchronize execution of the digitization of signals being treated with a system clock. Signals transmitted to such digital picture systems, after pretreated by a preliminary processor, are filtered to be frequency-synchronized in a phase synchronizing loop circuitry.